1. Field
This invention relates to stereoscopic visual systems. More particularly, this invention discloses an improved stereoscopic fluoroscopy system to provide three-dimensional visual presentations of fluoroscopic images.
2. State of the Art
Fluoroscopy techniques and apparatus are old and well known. See for example: U.S. Pat. No. 2,730,566 (Bertow et al). Attempts to obtain stereo or three-dimensional (3-D) images and particularly fluoroscopic stereo or 3-D images are known. U.S. Pat. No. 3,076,054 (Simon) discloses one such attempt using two sources of X-rays. A television system processes the X-ray images alternatingly received from the two sources into left and right video signals. The video signals are displayed to the viewer using polarization techniques. The left and right images are polarized differently and projected onto a screen using a half silvered mirror. The viewer wears simple polarized lenses in which the polarization is matched to the image polarization. The viewer orients his eyes (with the lenses) to permit simultaneous viewing of the left and right images on the screen to perceive a stereo type or 3-D type image.
Other attempts to produce a practical stereofluoroscopic system are also known. U.S. Pat. No. 3,309,519 (Euler, et al) discloses a system in which alternating color images developed from an X-ray source through television apparatus are displayed on a video screen. The viewer observes the images through color filter glasses to provide a stereo or 3-D perceived image.
The systems heretofore known have not achieved success or acceptance. Use of polarized glasses such as those disclosed by Simon force the viewer to maintain his eyes in a substantially fixed plane and orientation. Such constraints have proven to be impractical in that the viewer physically tires. As a result, the viewer either ceases to view after a short time or moves his head reducing the perceived quality of the presented image. Further, optical transmission is poor so that the perceived image is of poor quality. Use of color filters such as those employed by Euler et al has also been unsatisfactory. Distinct or narrow color filters are not practically available. As a result, the perceived image is of very poor quality. Representative color stereo photographs may be observed in M. Kunnen, Electro-medica, Siemeus Aktiengesellschaft 8520 Erlangen Henkestrasse 127 West Germany (1975 Vol. 1/75) at page 35 (stereo color filter viewing glasses included with publication). Eye strain and viewer distraction are typically experienced.
The advent of electro-optic light valves has rekindled interest in stereoscopic video systems. U.S. Pat. No. 3,821,466 (Roese) discloses a television system employing a light valve with a beam splitting device to act as a shutter mechanism for a television camera. Similar light valves are used by the viewer of a TV screen image to perceive the 3-D image. Lanthanum modified lead zirconate titante ceramics (PLZT) have also been used as light valves to achieve 3-D imagery. See U.S. Pat. No. 3,903,358 (Roese); c.f. J. A. Roese and A. S. Khalafalla, Stereoscopic Viewing with PLZT Ceramics, Ferroelectrics (Vol. 10, pp. 47-51) Gordon and Breach Science Publishers Ltd. (1976).
Prior to the use of light valves, various techniques have been disclosed to effect stereoscopic imagery. See, for example, U.S. Pat. Nos.: 3,527,880 (Gordon); 3,598,032 (Bohn); 3,858,001 (Bonne); 3,210,463 (Leenhardt); 2,696,523 (Theile); 3,621,127 (Hope); and 3,184,630 (Geer).
Although both stereoscopic video (e.g., TV) systems and stereo or 3-D fluoroscopic systems have been devised, practical 3-D or stereo fluoroscopic apparatus is yet unknown. Systems heretofore devised do not provide means to accommodate varying interocular separations of viewers or provide means to maximize perceived depth perception for particular objects. Further, known systems do not permit viewers to adjust perceived depth to the viewer's comfort. It may also be noted that many systems heretofore devised resort to optical or light beam splitting techniques [e.g., U.S. Pat. Nos. 3,903,358 (Roese); 3,821,466 (Roese); and 3,076,054 (Simon)] which significantly reduce clarity and resolution. That is, use of a beam splitter typically results in at least a 50% loss of light transmission with concomitant reduction in the quality of displayed and perceived image.
It may also be noted that no known stereofluoroscopic apparatus is available which provides the viewed with freedom of movement about the viewing device (e.g., TV screen), provides for multiple viewers and provides means and apparatus for the viewer to control the radiation delivered to the patient or object and the quality or character of the perceived image. Further, no known device is practically adaptable to existing two-dimensional fluoroscopy systems or which provides reverse or rear image perception means.